Project Summary The ?Ocular Hypertension Treatment Study (OHTS 3): 20-year follow-up (Phase 3)? was designed to determine the incidence and severity of primary open angle glaucoma (POAG) in the longstanding OHTS cohort. and determine the frequency and severity of functional limitations associated with POAG. Moreover, this well-characterized cohort has precise information on the dates/timing of the development of POAG assessed by 3 glaucoma specialist endpoint committee members, as well as extensive data on self-reported functional limitations of its participants. Spectral domain optical coherence tomography (OCT), now the standard of care for detecting glaucomatous structural damage and change was included for the first time in OHTS as part of the OHTS 3 core visit. The objective of this secondary data analysis proposal is to analyze the OHTS 3 OCT scans and leverage the 20 years of OHTS data to provide guidance on how best to utilize OCT in the clinical management of glaucoma. Specific Aim 1 will determine whether review of macula scans improves POAG detection compared to the clinical standard review of VF and RNFL scans. With the increased focus on patient-reported outcomes as a key measure of treatment success, in Specific Aim 2 we will utilize the extensive quality of life (QOL) surveys from OHTS 3 and include OCT structural damage in models to predict functional limitations due to POAG. Finally, with a participant median age of 73 years at the OHTS 3 core visit, Specific Aim 3 will characterize structural damage and its determinants 10 and 15 years after the precise onset of POAG and compare it to age-related structural changes in these older subjects who did not develop POAG.